Motor

Abstract

To efficiently cool a coil of a stator.SOLUTION: In a motor, a stator has: a stator core having a first end surface and a second end surface in the axial direction; and a coil, wound around the stator core, which has a first coil end provided on the first end surface and a second coil end provided on the second end surface. A case has a contact surface which comes into contact with the first end surface of the stator core. The contact surface is provided with an annular groove which annularly extends around a central axis of the stator. A space surrounded by the annular groove and the first end surface defines an annular cooling liquid passage where a cooling liquid flows. The stator is provided with: multiple first internal cooling liquid passages which extend from the first end surface to the second end surface, and which are connected to the annular cooling liquid passage; and a second internal cooling liquid passage which branches from each of the first internal cooling liquid passages and extends to the first end surface.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a motor.

[0002] The motor disclosed in Patent Document 1 has a stator core with an oil flow path formed therein. The stator core can be cooled by flowing oil through the oil flow path. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-114085 Summary of the Invention [Problem to be solved by the invention]

[0004] This specification proposes a technique for efficiently cooling the stator coil. [Means for solving the problem]

[0005] The motor disclosed in this specification includes a stator and a case that houses the stator. The stator includes a stator core and a coil. The stator core is cylindrical and has a first end face and a second end face located axially opposite the first end face. The coil is wound around the stator core. The coil has a first coil end provided on the first end face and a second coil end provided on the second end face. The case has an abutment surface that abuts against the first end face of the stator core. The abutment surface has an annular groove that extends annularly around the central axis of the stator. The space surrounded by the annular groove and the first end face forms an annular coolant flow path through which a coolant flows. The stator includes a plurality of first internal coolant flow paths that extend from the first end face to the second end face and are connected to the annular coolant flow path, and a second internal coolant flow path that branches off from the first internal coolant flow path and extends to the first end face.

[0006] In this motor, coolant flows from the annular coolant flow path to each of the first internal coolant flow paths. The coolant in the first internal flow paths cools the stator core and coils. The coolant in the first internal flow paths is discharged from the second end face toward the second coil ends, thereby cooling the second coil ends. Furthermore, some of the coolant in the first internal flow paths is discharged from the first end face toward the first coil ends via the second internal coolant flow paths, thereby cooling the first coil ends. In this way, this motor allows the stator coils to be efficiently cooled. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is an exploded perspective view of the motor according to the embodiment. [Figure 2] 2a is a partial cross-sectional view of the motor according to the embodiment, and FIG. 2b is a plan view of the annular groove 58. FIG. [Figure 3] FIG. 2 is an enlarged cross-sectional view of the motor according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] The motor 10 of the first embodiment shown in Figures 1 and 2 has a rotor 20, a stator 30, and a case 50. The rotor 20 has a shaft 24. The stator 30 has a cylindrical shape. The rotor 20 is disposed in a central hole of the stator 30 so that the central axis of the shaft 24 coincides with the central axis AX of the stator 30. The rotor 20 and the stator 30 are housed in the case 50. Hereinafter, the direction parallel to the motor shaft (i.e., the central axis AX) will be referred to as the axial direction, and the direction along a circle centered on the motor shaft will be referred to as the circumferential direction.

[0009] The stator 30 includes a stator core 32 and a coil 40. The coil 40 is wound around the stator core 32.

[0010] The stator core 32 is composed of multiple electromagnetic steel plates stacked in the axial direction. The stator core 32 has a cylindrical shape concentric with the central axis AX. The stator core 32 has a first end face 32a and a second end face 32b on both sides in the axial direction. The first end face 32a is located opposite the second end face 32b. Although not shown, the stator core 32 has multiple teeth on its inner circumferential surface. The coil 40 is wound around each tooth of the stator core 32. The coil 40 has a coil end 42a and a coil end 42b. The coil ends 42a and 42b are bent portions of the coil 40 wound around the stator core 32. The coil end 42a is provided on the first end face 32a. The coil end 42a protrudes from the first end face 32a. The coil end 42b is provided on the second end face 32b. The coil ends 42b protrude from the second end face 32b. As shown in Fig. 1, the coil ends 42b are distributed in an annular pattern on the second end face 32b. Similarly, the coil ends 42a are distributed in an annular pattern on the first end face 32a.

[0011] As shown in FIGS. 1 and 2 , the case 50 has an outer peripheral wall 52 and a partition wall 54. The outer peripheral wall 52 has a cylindrical shape. The partition wall 54 is provided at one axial end of the outer peripheral wall 52. A step portion 56 is provided on the inner surface of the case 50 at the boundary between the outer peripheral wall 52 and the partition wall 54. The step portion 56 is provided in an annular shape along the outer peripheral wall 52. The rotor 20 and the stator 30 are housed inside the outer peripheral wall 52. The stator core 32 is fixed to the case 50 with a plurality of bolts 49. The step portion 56 abuts against the first end face 32a of the stator core 32. The step portion 56 abuts against the first end face 32a on the outer circumferential side of the coil end 42a. The partition wall 54 of the case 50 faces the first end face 32a of the stator core 32. A gap is provided between the partition wall 54 and the first end surface 32a, and the coil end 42a is disposed within this gap. The partition wall 54 has a through hole 54a formed in its center.

[0012] The rotor 20 is arranged concentrically with the stator core 32 and in the center hole of the stator core 32. The shaft 24 of the rotor 20 is inserted into the through-hole 54a of the case 50. The rotor 20 is rotatably supported within the case 50 by a bearing or the like.

[0013] As shown in FIGS. 2 and 3 , an annular groove 58 is formed on the surface of the stepped portion 56. The annular groove 58 extends annularly along the stepped portion 56. The annular groove 58 has a circular shape that goes around the central axis AX. The opening of the annular groove 58 is closed by the first end face 32a of the stator core 32. The space surrounded by the annular groove 58 and the first end face 32a defines an annular coolant flow path 60. A coolant flows through the annular coolant flow path 60. In this embodiment, the coolant is oil. The oil functions as both a coolant and a lubricant that lubricates various parts of the motor 10. The first end face 32a of the stator core 32 is pressed toward the stepped portion 56 by the bolts 49. Therefore, the first end face 32a is in close contact with the surface of the stepped portion 56 around the annular groove 58, preventing the coolant in the annular coolant flow path 60 from leaking from the interface between the first end face 32a and the stepped portion 56. The surface of the stepped portion 56 (i.e., the surface around the annular groove 58) may be a surface formed by a cutting process. By using a cutting process, the surface of the stepped portion 56 can be formed with high surface accuracy, and the first end face 32a can be more appropriately brought into close contact with the stepped portion 56. Furthermore, a sealing material (e.g., a liquid gasket, an O-ring, etc.) may be provided at the interface between the first end face 32a and the stepped portion 56 to improve the sealing performance of the interface.

[0014] 2 and 3, a plurality of first internal coolant flow paths 39a are provided inside the stator core 32. Each of the first internal coolant flow paths 39a extends along the axial direction. One end of each of the first internal coolant flow paths 39a opens to the first end face 32a and is connected to the annular coolant flow path 60. The other end of each of the first internal coolant flow paths 39a opens to the second end face 32b near the coil end 42b. The multiple first internal coolant flow paths 39a are provided dispersed in the circumferential direction.

[0015] A plurality of second internal coolant flow paths 39b are provided inside the stator core 32. Each second internal coolant flow path 39b branches off from the corresponding first internal coolant flow path 39a and extends to the first end face 32a. That is, one end of each second internal coolant flow path 39b is connected to the corresponding first internal coolant flow path 39a, and the other end of each second internal coolant flow path 39b opens to the first end face 32a near the coil end 42a. The cross-sectional area of ​​each second internal coolant flow path 39b is smaller than the cross-sectional area of ​​each first internal coolant flow path 39a.

[0016] As shown in FIG. 3, a coolant supply path 62 is provided in the case 50. The coolant supply path 62 connects the outside of the case 50 to the annular coolant flow path 60. As shown in FIG. 2, a coolant discharge path 64 is provided in the lower part of the case 50. The coolant discharge path 64 connects the inside and outside of the case 50. The coolant discharge path 64 is connected to the coolant supply path 62 via a circulation path (not shown) provided outside the case 50. A pump (not shown) is provided in the circulation path. Coolant (i.e., oil) is stored inside the case 50. The pump sends the coolant stored in the case 50 from the coolant discharge path 64 to the coolant supply path 62.

[0017] When the motor 10 is operating, the pump operates and sends the coolant stored in the case 50 from the coolant discharge passage 64 to the coolant supply passage 62. The coolant flows from the coolant supply passage 62 into the annular coolant flow passage 60. The coolant in the annular coolant flow passage 60 flows into each of the first internal coolant flow passages 39a. The coolant in the first internal coolant flow passages 39a cools the stator core 32. The coolant in the first internal coolant flow passages 39a is discharged from the second end face 32b. The coolant discharged from the second end face 32b splashes on the coil ends 42b, cooling the coil ends 42b. A portion of the coolant in the first internal coolant flow passage 39a flows into the second internal coolant flow passage 39b. The coolant in the second internal coolant flow passage 39b is discharged from the first end face 32a. The coolant discharged from the first end surface 32a falls on the coil end 42a, thereby cooling the coil end 42a. In this manner, the coil ends 42a, 42b are cooled, and therefore the coil 40 is cooled efficiently.

[0018] As described above, the configuration of the motor 10 of the embodiment allows for efficient cooling of the coils 40 and the stator core 32. Therefore, a current can be passed through the motor 10 at a high current density. Furthermore, the configuration of the motor 10 allows for the annular coolant flow path 60 to be formed by bringing the first end surface 32a of the stator core 32 into contact with the stepped portion 56 having the annular groove 58 formed therein, thereby simplifying the structure of the motor 10.

[0019] In the above embodiment, one second internal coolant flow path 39b is provided for one first internal coolant flow path 39a, but multiple second internal coolant flow paths may be provided for one first internal coolant flow path 39a. Also, any of the multiple first internal coolant flow paths 39a may not be provided with a second internal coolant flow path.

[0020] Although the embodiments have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings simultaneously achieves multiple objectives, and achieving one of these objectives itself has technical utility. [Explanation of symbols]

[0021] 10: Motor 20:Rotor 30: Stator 32: Stator core 32a: First end surface 32b: Second end surface 39a: First internal coolant flow path 39b: Second internal coolant flow path 42a: Coil end 42b: Coil end 58: Annular groove 60: Annular coolant flow path

Claims

[Claim 1] A motor, a stator; a case that houses the stator; and The stator is a stator core having a cylindrical shape and including a first end surface and a second end surface located on the opposite side of the first end surface in an axial direction; a coil wound around the stator core, the coil having a first coil end provided on the first end surface and a second coil end provided on the second end surface; and the case has an abutment surface that abuts on the first end surface of the stator core, The abutment surface is provided with an annular groove extending annularly around the central axis of the stator, a space surrounded by the annular groove and the first end surface forms an annular coolant flow path through which a coolant flows, The stator has: a plurality of first internal coolant passages extending from the first end surface to the second end surface and connected to the annular coolant passage; a second internal coolant flow path branching from the first internal coolant flow path and extending to the first end surface; A motor is provided.

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